<template>
  <div id="viewport" data-type="viewport" class="holder">
    <div
      :style="{
        height: page.height + 'px',
        width: page.width + 'px',
        backgroundImage: 'url(' + backImg + ')',
      }"
      class="screen"
    >
      <!-- 组件 -->
      <component
        v-for="val in widgetStore"
        :is="val.type"
        :data-title="val.type"
        :class="{ active: widgetId === val.uuid }"
        :key="val.uuid"
        :val="val"
        :data-type="val.type"
        :data-uuid="val.uuid"
        class="layer"
      />

      <!-- 参考线 -->
      <!-- <ref /> -->

      <!-- 尺寸控制器 -->
      <control />
    </div>
  </div>
</template>

<script>
  import { defineComponent } from 'vue';
  import control from './size-control.vue';
  import move from '../mixins/move';
  import { usePrintDesignerStore } from '../store/printDesigner';

  export default defineComponent({
    components: {
      control, // 尺寸控制
    },

    mixins: [move],
    setup() {
      const printDesignerStore = usePrintDesignerStore();
      return {
        printDesignerStore,
      };
    },

    data() {
      return {};
    },

    computed: {
      // 已添加的组件
      widgetStore() {
        return this.printDesignerStore.page.tempItems;
      },
      // 背景图地址
      backImg() {
        return this.printDesignerStore.page.imageUrl ? this.printDesignerStore.page.imageUrl : '';
      },

      // 画布高度
      page() {
        return this.printDesignerStore.page;
      },
      // 选中项id
      widgetId() {
        return this.printDesignerStore.uuid;
      },
    },

    mounted() {
      // 采用事件代理的方式监听元件的选中操作
      let viewportDom = document.getElementById('viewport');
      if (viewportDom) {
        viewportDom.addEventListener('mousedown', this.handleSelection, false);
      } else {
        console.error('未找的‘viewport’节点');
      }

      // 绑定键盘上下左右键用于元件的移动
      document.addEventListener(
        'keydown',
        (e) => {
          e.stopPropagation();
          var target = this.printDesignerStore.activeElement;
          // 左
          if (e.keyCode === 37 && target.left) {
            target.left -= 1;
            return;
          }
          // 上
          if (e.keyCode === 38 && target.top) {
            e.preventDefault();
            target.top -= 1;
            return;
          }
          // 右
          if (e.keyCode === 39 && target.left) {
            target.left += 1;
            return;
          }
          // 下
          if (e.keyCode === 40 && target.top) {
            e.preventDefault();
            target.top += 1;
          }
        },
        true,
      );
    },

    methods: {
      /**
       * 目标元素获得焦点
       */
      handleSelection(e) {
        var target = this.selectTarget(e.target);
        if (target) {
          var uuid = target.getAttribute('data-uuid');
          // 设置选中元素
          this.printDesignerStore.select({
            uuid: uuid || -1,
          });
          // 绑定移动事件：除背景图以外的元件才能移动
          target = this.printDesignerStore.activeElement;
          if (target.draggable) {
            this.initmovement(e); // 参见 mixins
          }
        } else {
          // 取消选中元素
          this.printDesignerStore.select({
            uuid: -1,
          });
        }

        return true;
      },
      /**
       * 获得选中的目标，如果没有返回false
       */
      selectTarget(target) {
        let type = target.getAttribute('data-type');
        if (type) {
          if (type === 'viewport') {
            return false;
          } else {
            return target;
          }
        } else {
          return this.selectTarget(target.parentNode);
        }
      },
    },
  });
</script>

<style scoped>
  .holder {
    display: flex;
    justify-content: center;
    overflow: auto;
    font-size: 0;
    border: 1px solid #f5f5f5;
    border-width: 0 1px;
    background-image: linear-gradient(45deg, #f5f5f5 25%, transparent 0, transparent 75%, #f5f5f5 0),
      linear-gradient(45deg, #f5f5f5 25%, transparent 0, transparent 75%, #f5f5f5 0);
    background-position: 0 0, 13px 13px;
    background-size: 26px 26px;
  }
  .screen {
    margin: 25px auto;
    transform-origin: center top;
    position: relative;
    box-shadow: 0 0 5px 1px #cccccc;
    background-color: #ffffff;
    background-repeat: no-repeat;
  }
</style>
